Continuously variable transmission

ABSTRACT

A continuously variable transmissions (CVT), includes a main axle adapted to receive a shift rod that cooperates with a shift rod nut to actuate a ratio change in a CVT. An axial force generating mechanism can include a torsion spring, a traction ring adapted to receive the torsion spring, and a roller cage retainer configured to cooperate with the traction ring to house the torsion spring. Power roller-leg assemblies can be used to facilitate shifting the ratio of a CVT. A hub shell and a hub cover are adapted to house components of a CVT and, in some embodiments, to cooperate with other components of the CVT to support operation and/or functionality of the CVT. Among other things, shift control interfaces and braking features for a CVT are disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/664,035, filed on Dec. 10, 2009 and scheduled to issue on Feb. 4,2014 as U.S. Pat. No. 8,641,577, which is a national phase applicationof International Application No. PCT/US2008/066200, filed Jun. 6, 2008,which claims the benefit of U.S. Provisional Application No. 60/943,273,filed Jun. 11, 2007. The disclosures of all of the above-referencedprior applications, publications, and patents are considered part of thedisclosure of this application, and are incorporated by reference hereinin their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The field of the invention relates generally to transmissions, and moreparticularly to continuously variable transmissions (CVTs).

Description of the Related Art

There are well-known ways to achieve continuously variable ratios ofinput speed to output speed. The mechanism for adjusting an input speedfrom an output speed in a CVT is known as a variator. In a belt-typeCVT, the variator consists of two adjustable pulleys having a beltbetween them. The variator in a single cavity toroidal-type CVT has twopartially toroidal transmission discs rotating about a shaft and two ormore disc-shaped power rollers rotating on respective axes that areperpendicular to the shaft and clamped between the input and outputtransmission discs.

Embodiments of the invention disclosed here are of the spherical-typevariator utilizing spherical speed adjusters (also known as poweradjusters, balls, sphere gears or rollers) that each has a tiltable axisof rotation; the speed adjusters are distributed in a plane about alongitudinal axis of a CVT. The speed adjusters are contacted on oneside by an input disc and on the other side by an output disc, one orboth of which apply a clamping contact force to the rollers fortransmission of torque. The input disc applies input torque at an inputrotational speed to the speed adjusters. As the speed adjusters rotateabout their own axes, the speed adjusters transmit the torque to theoutput disc. The input speed to output speed ratio is a function of theradii of the contact points of the input and output discs to the axes ofthe speed adjusters. Tilting the axes of the speed adjusters withrespect to the axis of the variator adjusts the speed ratio.

SUMMARY OF THE INVENTION

The systems and methods herein described have several features, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope as expressed by the claims that follow, itsmore prominent features will now be discussed briefly. After consideringthis discussion, and particularly after reading the section entitled“Detailed Description of Certain Inventive Embodiments” one willunderstand how the features of the system and methods provide severaladvantages over traditional systems and methods.

One aspect of the invention relates to a power roller assembly for acontinuously variable transmission (CVT). The power roller assemblyincludes a generally spherical power roller having a central bore. Inone embodiment, the power roller assembly has a roller axle operablycoupled to the central bore. The power roller assembly can include a legcoupled to the roller axle. The leg has a first end and a second end.The first end has a roller axle bore and the second end has a shift camguide surface. The leg has a tapered surface between the first end andthe second end.

Another aspect of the invention concerns a continuously variabletransmission (CVT) having a plurality of power roller-leg assemblies.Each power roller-leg assembly has a skew-shift reaction roller. In oneembodiment, the CVT has a single-piece carrier having a substantiallycylindrical hollow body. The carrier operably couples to each of thepower roller-leg assemblies. Each of the power roller-leg assemblies arearranged at least in part on an interior of the hollow body. The carriercan be configured to contact each of the skew-shift reaction rollers onthe interior of the hollow body.

Yet another aspect of the invention involves a carrier for acontinuously variable transmission (CVT). The carrier has a generallycylindrical hollow body having a first end and a second end. In oneembodiment, the carrier includes a first support axle coupled to thefirst end. The first support axle extends axially from a first endexterior surface. The carrier can include a second support axle coupledto the second end. The second support axle extends axially from a secondend exterior surface. The carrier has a number of openings arrangedradially about the outer periphery of the cylindrical hollow body. Thecarrier also has a first set of radial grooves formed on a first endinterior surface, and a second set of radial grooves formed on a secondend interior surface. The first and second sets of radial grooves areeach configured to couple to a respective plurality of skew-shiftreaction rollers of the CVT.

One aspect of the invention concerns a power input assembly for acontinuously variable transmission (CVT). The power input assemblyincludes a cam driver having a first face, a second face, and an innerbore. The first face has a set of ramps. The power input assemblyincludes a torsion plate operably coupled to the cam driver. In oneembodiment, the power input assembly has a group of pawls operablycoupled to the torsion plate. Each of the pawls are operably coupled tothe inner bore of the cam driver. The pawls are configured to facilitatea transfer of torque from the torsion plate to the cam driver in a firstdirection.

Another aspect of the invention relates to a power input assembly for acontinuously variable transmission (CVT). The power input assemblyincludes a traction ring and a load cam roller cage operably coupled tothe traction ring. The load cam roller cage has a group of load camrollers. In one embodiment, the power input assembly includes a load camdriver operably coupled to the load cam roller cage. The load cam driverhas a set of ramps operably coupled to the load cam rollers. The loadcam driver has a groove formed on an outer circumference. The powerinput assembly also includes a torsion spring coupled to the load camroller cage and to the load cam driver. The torsion spring is located inthe groove of the load cam driver.

Yet one more aspect of the invention addresses a method of assembling acontinuously variable transmission (CVT) having a set of powerroller-leg assemblies, a housing cover, and a traction ring coupled toeach of the power roller-leg assemblies. The method includes providing aroller cage operably coupled to the traction ring. In one embodiment,the method includes providing a drive washer operably coupled to theroller cage. The method also includes installing a shim between thedrive washer and the housing cover. The shim is configured to provide anaxial pre-load force of the CVT.

In another aspect, the invention concerns a shifter interface assemblyfor a continuously variable transmission (CVT) having a main axle. Theshifter interface assembly includes a shift rod arranged at least inpart in a hollow bore of the main axle. In one embodiment, the shifterinterface has a ball bearing coupled to the shift rod and to the mainaxle. The shifter interface also includes a shift retainer nut coupledto the ball bearing and coupled to the main axle.

Another aspect of the invention relates to a shifter interface assemblyfor a continuously variable transmission (CVT) having a main axlearranged along a longitudinal axis. The shifter interface assemblyincludes a shift rod having an elongated body. The shift rod can bepositioned in a hollow bore of the main axle wherein at least a portionof the shift rod is enclosed by the main axle. The shifter interfaceassembly includes a clip coupled to the shift rod. In one embodiment,the shifter interface assembly has a first groove formed on the shiftrod. The first groove can be configured to receive an o-ring. Theshifter interface assembly can also include a second groove formed onthe shift rod. The second groove can be configured to receive the clip.The shift rod and the main axle are configured relative to each othersuch that the first groove is located inside the hollow bore of the mainaxle and the second groove is located outside of the hollow bore.

One aspect of the invention relates to a method of assembling acontinuously variable transmission (CVT). The method includes providinga brake adapter having a first substantially flat surface, a shoulderextending radially outward from the first flat surface, and a pilotingsurface arranged at least partly on an inner circumference of the flatsurface. The piloting surface extends axially from the first flatsurface. In one embodiment, the method includes providing a housingcover having a second substantially flat surface, an annular recesssubstantially surrounding the second flat surface, and an inner bore.The method can include placing the piloting surface in the inner bore.The method can also include aligning the first flat surface with thesecond flat surface. The first flat surface is in contact with thesecond flat surface. The method include providing a retaining ring. Inone embodiment, the method includes aligning the retaining ring tosurround the shoulder and the annular recess. The method can alsoinclude fastening the retaining ring to enclose the shoulder and theannular recess such that the retaining ring rigidly couples the brakeadapter to the housing cover.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-section of one embodiment of a continuously variabletransmission (CVT).

FIG. 2A is a detail view A, of the cross-section shown in FIG. 1,showing generally a variator subassembly.

FIG. 2B is a perspective view of certain components of the CVT, shown inFIG. 1, generally illustrating a cage subassembly of the variatorsubassembly.

FIG. 2C is a cross-section of one embodiment of an idler subassembly forthe CVT shown in FIG. 1.

FIG. 2D is a perspective, exploded view of the idler subassembly of FIG.2C.

FIG. 2E is a cross-section of one embodiment of the idler subassembly ofFIG. 2C as implemented with other components of the CVT shown in FIG. 1.

FIG. 3A is a detail view B, of the cross-section shown in FIG. 1,generally illustrating a power input subassembly.

FIG. 3B is a perspective, cross-sectional view of certain CVT componentsshown in FIG. 3A.

FIG. 3C is a cross-sectional view of certain components of the powerinput subassembly shown in FIG. 3A.

FIG. 4A is a detail view C, of the cross-section shown in FIG. 1,generally showing an input side axial force generation subassembly.

FIG. 4B is an exploded, perspective view of various components of theaxial force generation subassembly of FIG. 4A.

FIG. 5 is a detail view D, of the cross-section shown in FIG. 1,generally showing an output side axial force generation subassembly.

FIG. 6 is a detail view E, of the cross-section shown in FIG. 1,generally showing a shifter interface subassembly for a CVT.

FIG. 7 is a cross-section of yet another embodiment of a continuouslyvariable transmission (CVT).

FIG. 8A is a detail view F, of the cross-section shown in FIG. 7,showing generally a variator subassembly.

FIG. 8B is a perspective view of certain components of the variatorsubassembly shown in FIG. 8A.

FIG. 8C is a perspective, cross-sectional view of the components shownin FIG. 8B.

FIG. 8D is a perspective, cross-sectional view of an alternativeembodiment of certain components of the variator subassembly shown inFIG. 8A.

FIG. 8E is a perspective, cross-sectional view of an alternativeembodiment of certain components of the variator subassembly shown inFIG. 8A.

FIG. 8F is a perspective, cross-sectional view of an alternativeembodiment of certain components of the variator subassembly shown inFIG. 8A.

FIGS. 8G-I are perspective and cross-sectional views of an alternativeembodiment of certain components of the variator subassembly shown inFIG. 8A.

FIG. 8J is a cross-sectional view of an alternative embodiment of a leg.

FIG. 8K is a perspective view of the leg of FIG. 8G.

FIG. 8L is a cross-sectional view of an alternative embodiment of a leg.

FIG. 8M is a perspective view of the leg of FIG. 8I.

FIG. 8N is a perspective, cross-sectional view of one embodiment of atraction ring.

FIG. 8P is a cross-sectional view of the traction ring of FIG. 8I.

FIG. 8Q is a cross-sectional view of one embodiment of certaincomponents of a variator subassembly.

FIG. 8R is a perspective view of one embodiment of a carrier assemblythat can be used with the variator subassembly shown in FIG. 8Q.

FIG. 8S is a perspective view of an alternative embodiment of a carrierthat can be used with the variator subassembly shown in FIG. 8Q.

FIG. 8T is a cross-sectional view of one embodiment of certaincomponents of an alternative variator subassembly.

FIG. 8U is a perspective view of an embodiment of a carrier that can beused with the variator subassembly shown in FIG. 8T.

FIG. 9A is a detail view G, of the cross-section shown in FIG. 7,generally illustrating a power input subassembly.

FIG. 9B is a perspective, exploded view of certain components of thepower input subassembly shown in FIG. 9A.

FIG. 9C is a cross-sectional view of an alternative power inputsubassembly.

FIG. 9D is a perspective view of an input driver that can be used withthe power input subassembly shown in FIG. 9C.

FIG. 9E is a cross-sectional view of an input driver that can be usedwith the power input subassembly shown in FIG. 9A.

FIG. 9F is a cross-sectional view of yet another alternative power inputsubassembly.

FIG. 9G is a cross-sectional view of an input driver that can be usedwith the power input subassembly shown in FIG. 9D.

FIG. 9H is a cross-sectional view of yet another alternative power inputsubassembly.

FIG. 9J is a perspective view of an input driver that can be used withthe power input subassembly shown in FIG. 9H.

FIG. 9K is a cross-sectional view of certain components of a power inputsubassembly.

FIG. 9L is a cross-sectional view of an input driver that can be usedwith the power input subassembly shown in FIG. 9G.

FIG. 9M is a perspective view of a bearing nut that can be used with thepower input subassembly shown in FIG. 9A.

FIG. 9N is a perspective view of another embodiment of a bearing nutthat can be used with the power input subassembly shown in FIG. 9A.

FIG. 9P is a perspective view of yet another embodiment of a bearing nutthat can be used with the power input subassembly shown in FIG. 9A.

FIG. 9Q is a perspective view of one embodiment of a main shaft that canbe used with the variator of FIG. 7.

FIG. 9R is a perspective view of another embodiment of a main shaft thatcan be used with the variator FIG. 7.

FIG. 9S is a cross-sectional detail view of certain components of analternative power input subassembly that can be used with the variatorsdescribed.

FIG. 9T is a perspective, sectioned, exploded view of certain componentsof a power input subassembly.

FIG. 9U is a perspective view of an embodiment of a torsion plate thatcan be used to facilitate an internal freewheel function in a variator.

FIG. 9V is a cross-sectional, detailed view of the torsion plate of FIG.9U.

FIG. 9W is a perspective, cross-sectional view of a load cam driver thatcan be used with the torsion plate of FIG. 9U.

FIG. 9X is a perspective view of an embodiment of a pawl that can beused with the torsion plate of FIG. 9U.

FIG. 10A is a detail view H, of the cross-section shown in FIG. 7,generally showing an output side axial force generation subassembly.

FIG. 10B is a perspective, cross-sectional view of a hub cover that canbe used with the subassembly shown in FIG. 10A.

FIG. 10C is a perspective view of certain components of the input sideaxial force generation subassembly shown in FIG. 10A.

FIG. 11A is a detail view I, of the cross-section shown in FIG. 7,generally showing a shifter interface subassembly.

FIG. 11B is a cross-sectional view of certain components of analternative shifter interface subassembly.

FIG. 11C is a cross-sectional view of certain components of one morealternative shifter interface subassembly.

FIG. 12A is a perspective view of an anti-rotation washer that can beused with the variator of FIG. 7.

FIG. 12B is a cross-sectional view of the anti-rotation washer of FIG.12A.

FIG. 12C is a perspective view of another anti-rotation washer that canbe used with the variator of FIG. 7.

FIG. 12D is a cross-sectional view of the anti-rotation washer of FIG.12C.

FIG. 13A is a cross-section of yet another embodiment of a continuouslyvariable transmission (CVT).

FIG. 13B is perspective, sectioned, exploded view of one embodiment of acover and certain associated components that can be used with thevariators described here.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

The preferred embodiments will be described now with reference to theaccompanying figures, wherein like numerals refer to like elementsthroughout. The terminology used in the descriptions below is not to beinterpreted in any limited or restrictive manner simply because it isused in conjunction with detailed descriptions of certain specificembodiments of the invention. Furthermore, embodiments of the inventioncan include several novel features, no single one of which is solelyresponsible for its desirable attributes or which is essential topracticing the inventions described. The CVT embodiments described hereare generally of the type disclosed in U.S. Pat. Nos. 6,241,636;6,419,608; 6,689,012; 7,011,600; 7,166,052; and U.S. patent applicationSer. Nos. 11/243,484 and 11/543,311. The entire disclosure of each ofthese patents and patent applications is hereby incorporated herein byreference.

As used here, the terms “operationally connected,” “operationallycoupled”, “operationally linked”, “operably connected”, “operablycoupled”, “operably linked,” and like terms, refer to a relationship(mechanical, linkage, coupling, etc.) between elements whereby operationof one element results in a corresponding, following, or simultaneousoperation or actuation of a second element. It is noted that in usingsaid terms to describe inventive embodiments, specific structures ormechanisms that link or couple the elements are typically described.However, unless otherwise specifically stated, when one of said terms isused, the term indicates that the actual linkage or coupling may take avariety of forms, which in certain instances will be readily apparent toa person of ordinary skill in the relevant technology.

For description purposes, the term “radial” is used here to indicate adirection or position that is perpendicular relative to a longitudinalaxis of a transmission or variator. The term “axial” as used here refersto a direction or position along an axis that is parallel to a main orlongitudinal axis of a transmission or variator. For clarity andconciseness, at times similar components labeled similarly (for example,control piston 582A and control piston 582B) will be referred tocollectively by a single label (for example, control pistons 582).

Embodiments of a continuously variable transmission (CVT), andcomponents and subassemblies therefor, will be described now withreference to FIGS. 1-12D. FIG. 1 shows a CVT 100 that can be used inmany applications including, but not limited to, human powered vehicles(for example, bicycles), light electrical vehicles, hybrid human-,electric-, or internal combustion powered vehicles, industrialequipment, wind turbines, etc. Any technical application that requiresmodulation of mechanical power transfer between a power input and apower sink (for example, a load) can implement embodiments of a CVT 100in its power train.

As illustrated in FIG. 1, in one embodiment the CVT 100 includes a shell102 that couples to a cover 104. The shell 102 and the cover 104 form ahousing that, among other things, functions to enclose most of thecomponents of the CVT 100. A main axle 106 provides axial and radialpositioning and support for other components of the CVT 100. Fordescriptive purposes only, the CVT 100 can be seen as having a variatorsubassembly 108 as shown in detail view A, an input subassembly 110 asshown in detail view B, an input-side axial force generation subassembly112 as shown in detail view C, an output-side axial force generationsubassembly 114 as shown in detail view D, and a shift rod and/orshifter interface subassembly 116 as shown in detail view E. It shouldbe understood that characterization of the CVT 100 in terms of thesesubassemblies is for illustration purposes only and does not necessarilyestablish that these subassemblies, or components included therein, mustall be present or configured exactly as shown in the CVT 100. Thesesubassemblies will now be described in further detail.

Referring now to FIGS. 2A-2E, in one embodiment the variator subassembly108 includes a number of traction power rollers 202 placed in contactwith an input traction ring 210, output traction ring 212, and a supportmember 214. A shift rod 216 threads into a shift rod nut 218, which islocated between and is adapted to interact with the shift cams 220. Asupport member bushing 232 is piloted by the main axle 106 andinterfaces with the shift rod nut 218. When the materials selected forthe main axle 106 and the shift rod nut 218 differ, it is preferable toavoid rough surface finishes on the harder of the two materials. A shiftrod nut collar 219 is mounted coaxially about the main axle 106 and ispositioned between the shift cams 220. The shift cams 220 contact thecam rollers 222. Each of several legs 224 couples on one end to a camroller 222. Another end of each leg 224 couples to a power roller axle226, which provides a tiltable axis of rotation for the power roller202. In some embodiments, the power roller axles 226 rotate freely withrespect to the legs 224, by the use of bearings for example, but inother embodiments the power roller axles 226 are fixed rotationally withrespect to the legs 224. As best seen in FIG. 2B, a stator plate 236 anda stator plate 238 couple to a number of stator rods 240 to form acarrier 242. In some embodiments, the number of stator rods 240 of thecarrier 242 is preferably less than 9, more preferably less than 7, evenmore preferably less than 6, and most preferably less than 5. Thecarrier 242 is configured to facilitate the axial and radial support ofthe power rollers 202 and the legs 224, among other things. In someembodiments, the carrier 242 is configured to be rotatable and to, thus,facilitate the transfer of power into or out of the CVT 100.

In the embodiment shown in FIG. 2A, the support member 214 rides onbearing balls 228 that are positioned between the support member 214 andthe shift cams 220. In some instances, for description purposes only,the power roller 202, power roller axle 226, leg 224, and cam roller 222are referred to collectively as the power roller-leg assembly 230.Similarly, at times, the support member 214, shift cams 220, supportmember bushing 232, shift rod nut collar 219, and other componentsrelated thereto, are referred to collectively as the idler assembly 234.FIGS. 2C-2D show one embodiment of the idler assembly 234. In additionto components already mentioned above, the idler assembly 234 in someembodiments includes retaining rings 244 and thrust washers 246. Theretaining rings 244 fit in snap ring grooves of the support bushing 232,and the thrust washers 246 are positioned between the retaining rings244 and the shift cams 220. In some embodiments, as shown in FIG. 2D,the ball bearings 228 may be encased in bearing cages 248. FIG. 2E showsthe idler assembly assembled on the main axle 106.

Turning now to FIGS. 3A-3C, one embodiment of a power input subassembly110 is depicted and will be described now. In one embodiment, the inputsubassembly 110 includes a freewheel 302 that couples to one end of aninput driver 304. In some embodiments, the freewheel 302 can be aone-way clutch, for example. A torsion plate 306 couples to another endof the input driver 304. A cam driver 308 couples to the torsion plate306. In the embodiment shown, the cam driver 308 and the torsion plate306 have mating splines and the cam driver 308 mounts coaxially with thetorsion plate 306.

In the embodiment illustrated, the input driver 304 rides on ballbearings 310A, 310B. One set of ball bearings 310A rides on a raceprovided by a bearing nut 312. A second set of ball bearings 310B rideson a race provided by a bearing race 314. The bearing nut 312 and thebearing race 314 fit over the main axle 106. In one embodiment, thebearing nut 312 threads onto the main axle 106, while the bearing race314 is pressed fit onto the main axle 106. As shown in FIG. 3A, theinput driver 304, the bearing nut 312, and the bearing race 314 areconfigured to provide the functionality of, for example, angular contactbearings.

The shell 102 rides on a radial ball bearing 316, which is supported onthe input driver 304. A seal 318 is placed between the shell 102 and theinput driver 304. A seal 320 is placed between the bearing race 314 andthe input driver 304. Another seal 321 is placed between the inputdriver 304 and the bearing nut 312. To react certain axial loads thatarise in the CVT 100, interposed between the cam driver 308 and theshell 102 there is a thrust washer 322 and a needle roller bearing 324.In this embodiment, the shell 102 is adapted to transmit torque into orout of the CVT 100. Hence, the shell 102, in certain embodiments, can beconfigured to both transfer torque and to react axial loads, since thethrust washer 322 and/or the needle roller bearing 324 transmit axialforce to the shell 102.

Referencing FIGS. 4A-4B now, one embodiment of an input-side axial forcegeneration subassembly (input AFG) 112 will be described now. The inputAFG 112 includes a cam driver 308 in contact with a number of load camrollers 406. The load cam rollers 406 are positioned and supported by aroller cage 404. The rollers 406 also contact a set of ramps 420 thatare, in this embodiment, integral with the input traction ring 210 (seeFIG. 4B for an illustration of exemplary ramps 420). As the cam driver308 rotates about the main axle 106, the cam driver 308 causes therollers 406 to ride up the ramps 420. This roll-up action energizes therollers 406 and thereby generates an axial force, as the rollers 406 arecompressed between the cam driver 308 and the ramps 420. The axial forceserves to clamp, or urge the input traction ring 210 against, the powerrollers 202. In this embodiment, the axial force generated is reacted tothe shell 102 through a needle bearing 324 and a thrust washer 322; insome embodiments, however, the thrust washer 322 is not used, but ratheran equivalent bearing race can be provided integral to the shell 102. Asillustrated, the needle bearing 324 is placed between the load camdriver 308 and the thrust washer 322. Preferably, the surfaces of thethrust washer 322 in contact with the shell 102 and the needle bearing324 are flat. In some embodiments, the needle bearing 324 includesneedles having profiles on the surfaces in contact with the thrustwasher 322 and the load cam driver 308. In one embodiment, the needlesof the needle bearing 324 have a straight, center portion and radiused,or curved, end portions (not shown).

Turning to FIG. 5 now, one embodiment of an output-side axial forcegeneration subassembly (output AFG) 114 is shown. A set of load camrollers 506, similar to the load cam rollers 406 discussed above, ispositioned and supported in a roller cage 505, which is similar to theroller cage 404. The rollers 506 are interposed between the outputtraction ring 212 and the shell cover 104. In some embodiments thenumber of load cam rollers 506 retained in the roller cage 404 can bebetween 8 and 16. In some embodiments, a surface 507 of the shell cover104 is adapted to react the rollers 506. In one embodiment, the reactionsurface 507 is flat; however, in other embodiments, the reaction surface507 has load cam ramps, such as ramps 420. FIG. 5 shows a gap betweenthe rollers 506 and the shell cover 104; however, after assembly of theCVT 100, the gap closes as the torsion springs 402, 503 cause therollers 406, 506 to ride up ramps 420, 520 on the input traction ring210 and output traction ring 212, respectively. Once the output tractionring 212 rotates about the main axle 106 under torque transfer from thepower roller 202, the rollers 506 travel further up the ramps 520, whichgenerates additional axial force as the rollers 506 are furthercompressed between the output traction ring 212 and the shell cover 104.

A shifter and/or shift rod interface subassembly 116 will be describednow with reference to FIG. 6. The shifter interface 116 serves, amongother things, to cooperate with a shifting mechanism (not shown) toactuate the shift rod 216 for changing the transmission ratio of the CVT100. The shifter interface 116 also serves to retain the shift rod 216and constrain the axial displacement of the shift rod 216. In theembodiment illustrated, the shifter interface 116 includes a shift rodretainer nut 602 adapted to receive the shift rod 216 and to mount aboutthe main axle 106. The shifter interface 116 can also include a nut 604adapted to be threaded on the shift rod retainer nut 602 for, amongother things, coupling the main axle 106 to a dropout (not shown) of abicycle and to prevent the shift rod retainer nut 602 from unthreadingoff the main axle 106 during operation of the shifter mechanism. Asshown in FIG. 6, the shifter interface 116 can also include an o-ring606 for providing a seal between the shift rod retainer nut 602 and theshift rod 216.

Referring to FIG. 1, the input assembly 110 allows torque transfer intothe variator 108. The input assembly 110 has a sprocket 156 thatconverts linear motion from a chain (not shown) into rotational motion.Although a sprocket is used here, other embodiments of the CVT 100 mayuse a pulley that accepts motion from a belt, for example. The sprocket156 transmits torque to an axial force generating mechanism, which inthe illustrated embodiment is an axial force generation assembly 112that transmits the torque to the input ring 210. The axial forcegeneration mechanism 112 transmits torque from the sprocket 156 to theinput ring 210 and generates an axial force that resolves into thecontact force for the input disc 210, the balls 202, the idler assembly234 and the output ring 212. The axial force is generally proportionalto the amount of torque applied to the axial force generating mechanism112. In some embodiments, the sprocket 156 applies torque to the axialforce generating mechanism 112 via a one-way clutch (detail not shown)that acts as a coasting mechanism when the CVT 100 spins but thesprocket 156 is not supplying torque.

In the embodiment of FIG. 1, a shift rod 1105 actuates a transmissionratio shift of the CVT 100. The shift rod 1105, coaxially located insidethe main shaft 106, is an elongated rod having a threaded end thatextends out one side of the main shaft 106 to connect to a shifterinterface assembly 116. The other end of the shift rod extends into theidler assembly 234, which mounts generally transversely in the shift rodnut 218, as shown in FIG. 2A. The shift rod nut 218 engages the idlerassembly 234 so that the shift rod 1105 can control the axial positionof the idler assembly 234.

An alternative embodiment of a CVT 700, and components and subassembliestherefor, will be described now with reference to FIGS. 7-12H. FIG. 7shows a cross-section view of CVT 700 similar in function to the CVT 100illustrated and described with reference to FIG. 1. In one embodiment,the CVT 700 includes a shell 702 that couples to a cover 704. The shell702 and the cover 704 form a housing to enclose most of the componentsof the CVT 700. A main axle 706 provides axial and radial positioningand support for other components of the CVT 700. The CVT 700 can bedescribed as having a variator subassembly 708 as shown in detail viewF, power input subassembly 710 as shown in detail view G, an input-sideaxial force generation 712 subassembly as shown in detail view J, anoutput-side axial force generation 714 as shown in detail view H, and ashift rod and/or shifter interface subassembly 716 as shown in detailview I. Alternative embodiments of these subassemblies will be describednow in further detail.

Referencing FIG. 8A, in one embodiment, the subassembly 708 includes anumber of traction power rollers 802 placed in contact with an inputtraction ring 810, output traction ring 812, and an idler subassembly834. Various embodiments of a power roller-leg assembly 800 andassociated components are shown and described with reference to FIGS.8B-8I.

One embodiment of the power roller-leg assembly 800 is illustrated inFIGS. 8B and 8C. The power roller-leg assembly 800 includes the tractionpower roller 802 supported on needle roller bearings 804 and a rolleraxle 826 having, in one embodiment, a constant diameter along the lengthof the roller axle 826. Spacers 806 are placed on each end of the rollerbearings 804, and one of the spacers 806 is located between the rollerbearings 804. The ends of the roller axle 826 extend beyond legs 824 andreceive skew rollers 808. The skew rollers 808 can be secured by aretaining washer 830 pressed onto the roller axle 826. The legs 824 canbe adapted to support shift guide rollers 809, which (among otherthings) provide a reaction surface to support a tilt motion of the powerroller-leg assembly 800 when the transmission ratio of the CVT 700 isadjusted.

Passing to FIGS. 8D and 8E, alternative ways to retain the skew roller808 onto the roller axle 826 will be described now. The skew roller 808can be retained with a clip 832A fixed to the roller axle 826 in agroove 832B formed into the roller axle 826, as shown in FIG. 8D.Alternatively, as shown in FIG. 8E, the skew roller 808 can be retainedon the roller axle 826 by deforming the ends of the roller axle 826 tocreate a cap 836. The cap 836 can be manufactured with an orbit formingtechnique well known in the relevant technology, for example. In someembodiments, the leg 824 is constructed to enclose substantially most ofthe end of the roller axle 826, as illustrated in FIG. 8F. In thislatter embodiment, the roller axle 826 is not provided with the skewrollers 808 as the leg 824 can directly provide the skew supportfunction. The skew roller 808 shown in FIGS. 8D and 8E are generallycylindrical with a central through bore mating with the roller axle 826.

Referring now to FIGS. 8G-8I, in one embodiment, a skew-shift reactionroller 860 includes a generally toriconical-shaped external surface anda central through bore, which central bore facilitates mating theskew-shift reaction roller 860 with the roller axle 826. In someembodiments, the skew-shift reaction roller 860 can be retained on theroller axle 826 with, for example, a clip 832. The skew-shift reactionroller 860 is preferably configured to provide simultaneously thesupport for reactions forces that arise from shifting and for reactionforces that arise from the phenomenon of skew. As discussed below withreference to FIGS. 8T and 8U, a carrier 862 can be configured tocooperate with the skew-shift reaction roller 860 so that the reactionforces from shifting and skewing can be reacted by a single skew-shiftreaction roller 860, rather than a combination of (for example) a skewroller 808 and a shift guide roller 809. Hence, a leg 827 that can beused with the skew-shift reaction roller 860 need not be provided with abore 823 (see FIG. 8C) for receiving an axle (not shown) for supportingthe shift guide roller 809. In some embodiments, a skew-shift roller 870can be generally spherical with a countersunk bore 872 to mate with theroller axle 826, as shown in FIGS. 8H and 8I. The leg 821 in thisembodiment can include a filleted shoulder 824C to provide clearance forthe skew-shift roller 870.

Referencing FIGS. 8K-8M now, in one embodiment a leg 824A can be a bodyhaving one end 850 and a second end 852, a roller axle bore 841, a guideroller axle bore 842, a shift cam guide surface 845, and a tapered sidesurface 843. In the embodiment illustrated in FIGS. 8K-8J, the rolleraxle bore 841 is substantially perpendicular to the guide roller bore842 and parallel to the central bore 844. In some embodiments, thetapered side surface 843 has very little taper (in some instances evenno taper at all) and is substantially parallel to the shift cam guidesurface 845; in other embodiments, the tapered side surface 843 isangled relative to the shift cam guide surface 845, resulting in the end850 having a width 851 larger than a width 853 of the second end 852. Insome embodiments, the end 850 and the tapered surface 845 can includechamfers 847, 848 and 846, as shown in FIG. 8J. The length of the rolleraxle bore 841 can be adjusted in embodiments of power roller-legassemblies using the skew rollers 808 as illustrated in FIGS. 8B-8E and8G-8I; however, in some embodiments, the power roller-leg assemblies donot use the skew rollers 808, as illustrated in FIG. 8F. In anotherembodiment, the leg 824B, shown in FIGS. 8L and 8M, includes a face 860located near one end 850 that is in contact with the stators 236 and238. Preferably, the power roller-leg assemblies 800 are configured tomaintain geometric compatibility with the associated interfaces in thevariator assembly 708.

Passing to FIGS. 8N-8P now, in one embodiment a traction ring 810 issimilar to the traction ring 812. The traction ring 810 can be agenerally annular ring having a set of ramps 852 on one side of thetraction ring 810. In certain embodiments, the ramps 852 can beunidirectional as shown; however, in other embodiments, the ramps 852can be bidirectional. A side of the traction ring 810 opposite to theramps 852 includes a conical, traction or friction surface 854 fortransmitting power to or receiving power from the power roller 802. Inthe embodiment shown in FIGS. 8N-8P, the traction ring 810 includes arecess 856 for receiving and supporting a torsion spring, such as thetorsion spring 402, for example. In some embodiments, a step 850 isformed into the traction ring 810 to, among other reasons; reduce theweight of the traction ring 810. In one embodiment, the step 850 is anannular recess that extends from one edge of the traction surface 854 toa lateral surface 857 of the traction ring 810. That is, in someembodiments, the traction surface 854 of the traction ring 810 does notextend to the lateral surface 857.

Turning now to FIGS. 8Q-8U, embodiments of a carrier will be describednow. As described previously, and illustrated in FIG. 2B, a carrier 242can be, among other things, an assembly having stator plates 236 and 238connected with rods 240 and having, among other attributes, grooves toguide the power roller-leg assembly 230, and can be rigidly connected toa central main axle 706. In other embodiments, carriers 872, 873depicted in FIGS. 8Q-8S can be used in a substantially similar manner asthe carrier 242.

As shown in FIG. 8Q, the power roller-leg assembly 801 having skew-shiftreaction rollers 870 can be configured to cooperate with the carrier 872and the idler assembly 834. In the embodiment illustrated, a firstsupport axle 707 can be coupled to one side of the carrier 872 and havea central through bore 7061 to allow, among other things, access forcoupling the shift rod 8805 with the idler assembly 834; a secondsupport axle 711 is coupled to a second side of the carrier 872. In thisembodiment, the shift rod 8805 is used to radially align and support theidler assembly 834 and is supported on one section by a bushing 8806constrained in the bore of the support axle 707 and on one end by abushing 8807 constrained in a bore 8808 of the second support axle 711.

The carrier 872, as shown in FIG. 8R, can be a generally cylindrical andhollow body 877 having openings 878 on the circumferential walls of thebody 877. In some embodiments, the first and second support axles 707,711 are formed (for example, by casting) as one integral piece with thebody 877. Preferably, the openings 878 are configured to form carrierlegs 880 that substantially provide a similar function to the statorrods 240. The openings 878 can be symmetrically arranged around thecircumference of the body 877; in some embodiments, the openings 878 areasymmetrically arranged so that an opening 876 provides, among otherthings, clearance for installing the idler assembly 834. In someembodiments, as shown in FIG. 8S, it is preferable for the openings 881and 883 to be configured to provide carrier legs 885 which aredimensionally larger than the carrier legs 880 and can structurallystrengthen the carrier 872, in particular, the carrier legs 885 areconfigured to provide torsional strength to the carrier 872. A number ofradial grooves 874 can be formed in the carrier 872 to guide theskew-shift rollers 870. In this embodiment, the radial grooves 874 havea substantially hemi-cylindrical profile for mating with the skew-shiftrollers 870. The radial grooves 874 react shift and skew forcestransmitted by the skew-shift rollers 870 that are generated eitherwhile shifting a CVT 700 or operating a CVT 700.

Referring to FIG. 8T, in one embodiment a carrier 862 that can be usedwith power roller-leg assemblies 803 having skew-shift rollers 860 isdescribed. The carrier 862 includes a generally hollow cylindrical body889 with openings 866 formed on the circumference of the body 889 toform carrier legs 880 and an access opening 868 and similar in functionto carrier 872. Preferably, a number of grooves 864 are formed into thebody 889 to guide and otherwise cooperate with the skew-shift rollers860. The grooves 865 in this embodiment can have a profile thatgenerally conforms to the toriconical shape of the skew-shift rollers860 with an adequate clearance groove 864 for the roller axle 826. Thegrooves 864 provide substantially similar function as the grooves 874for reacting skew and shift forces transmitted by the skew-shift rollers860. It should be readily apparent to the person having ordinary skillin the relevant technology that embodiments of the carriers 862, 872,and 873 can be modified for use with substantially cylindrical skewrollers 808 and shift guide roller 809 as shown in FIGS. 8B-8E; with thelegs 824, 824A, and 824B shown in FIGS. 8F and 8K-8M.

Turning to FIGS. 9A-9T, various embodiments of the power inputassemblies 710 are illustrated and will be described now. Fordescriptive purposes only, an input driver subassembly 900 can includean input driver 902, torsion plate 904, bearings 906, seal 908, spacer910, and bearing nut 912. In one embodiment, the torsion plate 904 isaffixed to the input driver 902, which has cartridge bearings 906pressed and retained on an inner diameter of the input driver 902 byshoulders 914 and 918 formed into the input driver 902 (see FIG. 9C). Acavity 916 can be formed on the inner diameter of the input driver 902in order to reduce component weight among other things. A seal 908 ispressed or affixed on the inner diameter of the input driver 902.

As shown in FIG. 9G, in one embodiment an input driver 952 is providedwith bearing races 922A and 922B. FIG. 9H shows an embodiment of aninput driver assembly 959 having a freewheel 924 threaded onto the inputdriver 954 and retained with a clip 928. In one embodiment, a slot 926is formed into the input driver 954. In yet another embodiment, an inputdriver assembly 956 (shown in FIG. 9K) includes ball bearings 906 withouter races 907. An input driver 958 has chamfers 930A and 930B on theinner diameter to retain the outer races 907 of the ball bearings 906.

FIGS. 9D, 9E, 9G, 9J, and 9L show alternative embodiments of an inputdriver. As shown in FIG. 9D, in one embodiment the outer diameter of theinput driver 902 has splines 932, a groove 936, and bearing surface 940and seal surface 942. In another embodiment, as shown in FIG. 9J, anouter diameter of an input driver 954 includes a threaded section 934, agroove 936, a key slot 926, and bearing surfaces 940 and seal surface942. Referencing FIG. 9G, in one embodiment, the inner diameter of theinput driver 952 can include bearing races 922A and 922B and a spiralgroove 920, which is preferably configured for delivering lubrication tothe bearings 906. As illustrated in FIG. 9E, the inner diameter of theinput driver 902 can be provided with bearing recesses 944 and 946 forreceiving cartridge bearings 906, which can be press fit, for example,onto the bearing recesses 944 and 946. In some embodiments, a groove 916is formed in the inner diameter of the input driver 902 to reduceweight, among other reasons. In one embodiment, the input driver 902includes shoulders 914 and 918 to locate the bearings 906. Withreference to FIG. 9L, for some applications the inner diameter of aninput driver 958 includes a spiral groove 920 between the two chamfers930A and 930B that retain and locate bearings 906. It should be readilyapparent to the person having ordinary skill in the relevant technologythat any one specific embodiment of an input driver suitable for usewith the transmissions described here can include any combination ofaspects described with reference to the various, exemplary embodimentsof input drivers described. For example, in one embodiment an inputdriver can include an outer diameter having the threaded portion 934 andan inner diameter having the bearing races 922A, 922B or, alternatively,the chamfers 930A, 930B.

Passing to FIGS. 9N-9R, various alternative embodiments of a bearing nutwill be described now. As shown in FIG. 9A, the bearing nut 912 ispositioned relative to the seal 908 in the input driver assembly 900 andthreads onto the main axle 706. Various embodiments of the bearing nutcan be provided to accommodate seal 908, or other components. In oneembodiment shown in FIG. 9M, a bearing nut 913 includes a threaded innerbore 948, a sealing surface 954, and flats 950 in an octagonal,arrangement. The sealing surface 954 is on the outer diameter of thebearing nut 913 and is configured to cooperate with the seal 908. Insome embodiments, the sealing surface 954 can also provide an innerbearing race for the input driver assembly 710. As shown in FIG. 9N, inanother embodiment, a bearing nut 915 can have a sealing shoulder 954A,parallel flats 952A, a threaded inner diameter 948A; and friction teeth956. The sealing shoulder 954A is configured to cooperate with the seal908 in some embodiments. The friction teeth 956 in some embodiments arein contact with a frame or structure, such as the dropouts of a bikeframe, and can be used as an anti-rotation member for the main axle 706during torque reaction. In an another embodiment, shown in FIG. 9P, abearing nut 917 has a threaded inner bore 948, parallel flats 952, and asealing surface 954, on the outer diameter of the bearing nut 917. Theembodiments of the bearing nut described can be modified to maintaingeometric compatibility at the interface between the bearing nut and theframe or a structure, such as dropouts of a bike frame.

Passing now to FIGS. 9Q and 9R, one embodiment of a main axle 706 willbe described. The main axle 706 has a first end having a flat 962 and asecond end having a flat 964 for, among other things, receiving themounting bracket, chassis or frame members such as the dropouts of abicycle, for example. A central portion of the main axle 706 has athrough slot 970 for receiving the shift rod nut 218. In certainembodiments, the main axle 706 is provided with a central bore 974adapted to receive, for example, the shift rod 1105. The central bore974 need not go through the entire length of the main axle 706. However,in other embodiments, the central bore 974 may extend through the entirelength of the main axle 706 for providing, for example, an access portor lubrication port. The main axle 706 also includes knurled or splinedsurfaces 978 that engage the stator plates 236 and 238. In oneembodiment, illustrated in FIG. 9Q, a main axle 709 includes two bearingsurfaces 958A and 958B for use with various embodiments of an inputdriver, such as those shown and described with reference to FIGS. 9D,9F, and 9G. Referencing FIG. 9R, in an alternative embodiment, a mainaxle 706 includes two bearing race seats 960A, 960B for use with, forexample, input driver embodiments shown in FIGS. 9B, 9C, and 9E. Thebearing race seats 960A, 960B are preferably formed to, among otherthings, retain the inner race of the cartridge bearings 906. In theembodiment illustrated in FIG. 9R, the main axle 706 includes a bearingpilot portion 982 for supporting a bearing 118. The main axle 706 mayadditionally include a bearing race piloting surface 960A for supportingthe bearing race 314 (see FIG. 3A and accompanying text).

Referring to FIG. 9S and FIG. 9T now, an input-side axial forcegeneration assembly 985 can include, among other things, a traction ring990 in contact with the power roller 802, and a load cam roller cage 992cooperating with a load cam driver 994. Axial forces generated at theload cam driver 994 are reacted axially by a bearing 998 and thrustwasher or race 999, which race 999 is in contact with the shell 702. Inone embodiment, a torsion spring 996 can be coupled to the load camroller cage 992 and to the cam driver 994 for providing preload on theload cam rollers 993. In some embodiments, a groove 995 can be formed onthe circumference of the load cam driver 994 to receive, support, and/orhouse the torsion spring 996.

Referring now to FIGS. 9U-9W, an embodiment of certain components of thepower input assembly will be described. A CVT can be provided aninternal freewheeling functionality with, among other things, a torsionplate 905 shown in FIG. 9U. The torsion plate 905 is provided with anumber of radial slots 9051 configured to receive and support pawls9052, which are configured to cooperate with a number of internal teeth9053 formed into, for example, a cam driver 9054 (FIG. 9V); the camdriver 9054 is substantially similar in function to the cam driver 994but also support the freewheeling of the CVT. In some embodiments, aretaining spring 9055 can be used to energize the pawls 9052. For someapplications, it is preferable to have minimal angular rotation beforeengagement in order to minimize lost motion on the input duringoperation of the CVT 700. For example, if it is determined that, in acertain application of the CVT 700, the maximum angular rotation of thetorsion plate 905 before engagement of the pawls 9052 with the internalteeth 9053 is five degrees, then there are several combinations of thenumber and radial arrangement of pawls 9052 on the torsion plate 905 andthe number of internal teeth 9053. In one embodiment, there can beseventy-two internal teeth 9053 and at least one pawl 9052, or multiplepawls 9052 arranged symmetrically on the torsion plate 905 so that allpawls 9052 in this embodiment engage the internal teeth 9053simultaneously. In other embodiments, the number of internal teeth maybe fewer, such as thirty-six, to facilitate manufacturing, for example,and in this embodiment the pawls 9052 can be arranged asymmetrically soa number of the pawls 9052 will engage the internal teeth 9053 and theremaining pawls 9052 will not be engaged and be positioned radiallybetween two internal teeth 9053. It should be readily apparent to aperson having ordinary skill in the relevant technology, that the numberof internal teeth 9053 and the number and arrangement of the pawls 9052are configurable to achieve the desired angular engagement.

Turning now to FIG. 9W, an embodiment of a pawl 9052 will be described.The pawl 9052 can be a body having a pivot end 9056 and an engagementend 9057. On the pivot end 9056 there can be retaining flanges 9058 thatcouple to the torsion plate 905 in such a way that the pawl 9052 isconstrained in the radial slots 9051. In some embodiments, there can beonly one retaining flange 9058 on one side of the pawl 9052 and theother side of the pawl can be retained in the radial slot 9051 by theretaining spring 9055. The retaining flanges 9058 are generally “D”shaped, that is there is a flat and a curved portion. The flat portionis in contact with the retaining spring 9055 and positions the pawl 9052in the radial slot 9051 so that the engagement end 9057 contacts theinternal teeth 9053.

Turning to FIGS. 10A-10C now, one embodiment of an output-side axialforce generation subassembly (output AFG) 714 is shown. In oneembodiment, the output AFG 714 includes the cover 704, shim 1004, outputdrive washer 1006, load cam rollers 1008, and roller cage 1010. The shim1004 is used in some embodiments to adjust the relative axial positionof the input and output axial force generation subassemblies 712 and714.

In some embodiments, referencing FIG. 10C, the cover 704 is made ofsteel or aluminum and can be provided with a thrust surface 1012 that isconfigured to contact either the load cam rollers 1008, the output drivewasher 1006 or, as depicted in FIG. 10A, the shim 1004. In someembodiments, a slot 1014 can be formed into the cover 704 facilitatealignment and retention of the thrust washer 1006. In one embodiment, atab 1016 is formed on the output drive washer 1006 and is configured tomate with the slot 1014. In some embodiments, there are two slots 1014and two tabs 1016. In other embodiments, there can be, for example, fourslots and four tabs for alignment.

Referencing FIGS. 11A-11 c, alternative embodiments of a shifterinterface subassembly will be described now. In some embodiments, theshifting mechanism for CVT 700 includes a shift rod 1105 and the mainaxle 706 arranged concentrically, as depicted in FIG. 11A. The shift rod1105 is retained by a shift rod retainer nut 1104 that is threaded ontothe main axle 706. The shift rod 1105 is connected to a shiftermechanism (not shown) for changing the ratio of the CVT 700. In someembodiments, a rider interfaces with the shifter mechanism via a handgrip that controls cables which are operationally coupled to a shiftpulley (not shown) and, thereby, to the shift rod 1105. The shift rod1105 is operably coupled to the idler assembly 834. During operation,axial forces are generated on the idler assembly 834 due to forces atthe traction contact formed between the traction power rollers 802 andthe idler assembly 834. These axial forces are reacted at an interfacebetween the shift rod 1105 and the main axle 706. In one embodiment, theinterface includes a flange 1108 on the shift rod 1105 and a step 1106on the main axle 706. In some embodiments, both the flange 1108 and thestep 1106 are made of steel. The material hardness of the shift rod 1105can be relatively soft (25-28 HRC) to accommodate the manufacturingprocesses to form other attributes on the shift rod 1105, such as acmethreads, splines, and o-ring groove 1107. In some instances, thematerial softness can result in the flange 1108 having a poor surfacefinish. The idler forces reacting through the shift rod 1105 against themain axle 706 generate a friction force at the flange 1108. The frictionforce by be overcome by the rider through the shifter mechanism and thehand grip during a shift event.

Passing to FIG. 11B now, an embodiment of an interface between a shiftrod 1109 and a main shaft 701 includes a ball bearing 1110. Bearingraces 1112 for bearing balls 1111 are formed into the shift retainer nut1104, the main axle 706, and the shift rod 1105. In one embodiment, theraces 1112 can be 30-degree flat faces and not fully conformal to thebearing balls 1111. In some embodiments, the bearing balls 1111 have amaterial hardness that is greater than a material hardness of the races1112; consequently, the bearing balls 1111 can wear and form the softerraces 1112 into a conformal race during operation. Alternatively, theraces 1112 can be formed to be conformal to the bearing balls 1111 atthe time of manufacture.

As shown in FIG. 11C, in one embodiment, a shift rod 1113 can beprovided with a groove 1114 for receiving a clip 1116A to provide thereaction interface with a main shaft surface 1118 of the main axle 706.In some embodiments, the shift rod 1113 can be provided with an o-ringgroove 1107 for receiving an o-ring 1115. The clip 1116A can be madefrom hardened steel wire and have, for example, a rectangular orcircular cross section. In some embodiments, the clip 1116A can beconstrained by the slot 1114. In this embodiment, the surface of theclip 1116A rotates during a shift event with respect to the main shaftface 1118 generating a friction force. In other embodiments, the clip1116A can be constrained by the main axle 706 and the shift rod retainernut 1104 so that the clip 1116A rotates in the shift rod slot 1114. Inthis embodiment the friction forces are generated between the faces ofthe slot 1114 and clip 1116A. It is generally preferable to reduce thefriction forces, for example, through better surface finishes on thefriction faces. Alternatively, the shift torque required can be reduced,for example, by reducing the radius where the friction forces aregenerated.

Turning to FIGS. 12A-12D now, alternative embodiments for anti-rotationwashers are described. Shown in FIG. 12A and FIG. 12B is an embodimentof an anti-rotation washer 726 that can be used in, for example, bikeframes having vertical or horizontal dropouts. In one embodiment, theanti-rotation washer 726 includes a cylindrical body having a front face1200 and back face 1204, a central bore 1203 with parallel flats 1205,and a reaction shoulder 1202. The back face 1204 is preferablyconfigured to cooperate with a jam nut similar to nut 1103 or othersimilar fastener. The front face 1200 has friction teeth 1201 locatedradially inward of an outer diameter of the cylindrical body and spacedangularly about an axis passing through the central bore 1203. In someinstances, the friction teeth 1201 are preferably configured to engagesurfaces of, for example, bike frame members. The reaction shoulder 1202protrudes from the front face 1200. In one embodiment, the reactionshoulder 1202 has a plurality of faces in contact with the dropout of abike frame and constrains the anti-rotation washer 726 from rotatingwith respect to the frame. A piloting surface 1212 can be provided toalign the washer in the dropout of a bike frame, for example to equalizethe two ends of the main axle 706 for horizontal alignment in verticaldropouts. The parallel flats 1205 are configured to mate to the mainaxle 706 and to prevent rotation of the main axle 706 with respect tothe anti-rotation washer 726 and, consequently, the dropout of the bikeframe.

An alternative anti-rotation washer 730 is shown in FIGS. 12C and 12D.The anti-rotation washer 730 has a front face 1209 and a back face 1211.The friction teeth 1201 are formed into a circumference of the frontface 1209. The back face 1211 can have a profile 1210 in some cases. Thethrough-hole 1207 can be used to support a bolt or fastener for couplingthe anti-rotation washer 730 to, for example, a bike frame. A slot 1208can be formed in the reaction arm 1202. The reaction arm 1202 protrudesfrom the front face 1209. The reaction arm 1202, in one embodiment,extends from the central bore to engage with the dropout of a bikeframe. This engagement prevents rotation of the anti-rotation washer 730with respect to the dropout. The parallel flats 1205 are preferablyconfigured to mate to the main axle 706 and prevent rotation of theanti-rotation washer 730 with respect to the main axle 706 and,consequently, prevent rotation between the main axle 706 and bike framedropout.

Passing now to FIG. 13A, certain components of a CVT 1300 will bedescribed now. In one embodiment, the CVT 1300 includes a cover 1302having a threaded circumference 1303 configured to mate with the shell702. A retaining ring 1304 is adapted to, among other things, secure orfasten a brake adapter 1306 to the cover 1302. In one embodiment, thecover 1302 has a substantially flat surface 1314 configured to mate to asubstantially flat surface 1316 formed on the brake adapter 1306. Thebrake adapter 1306 can have a piloting surface 1308 that engages aninternal diameter of the cover 1302 and be provided with a bearingshoulder 1322. In some embodiments, the retaining clip 1304 is agenerally cylindrical ring with a retaining shoulder 1318 on the innerdiameter. The retaining shoulder 1318 is preferably shaped to facilitateretaining the brake adapter 1306 against the cover 1302. In particular,in one embodiment, the inner diameter of the retaining clip 1304 issuitably formed into a shape that conforms to the combined profile of ashoulder 1310 on the brake adapter 1306 and an annular shoulder 1312 onthe cover 1302 to, thereby, clamp or secure the brake adapter 1306 tothe cover 1302. As shown in FIG. 13B, the annular shoulder 1312 can risefrom an annular recess 1313 formed in the cover 1302. Since in someembodiments the cover 1302 and the brake adapter 1306 are provided asseparate components, this facilitates the use of different materials forthe cover 1302 and the brake adapter 1306. In some embodiments, ano-ring groove 1320 can also be formed in the cover 1302 to retain ano-ring (not shown) to provide a seal between the cover 1302 and thebrake adapter 1306.

It should be noted that the description above has provided dimensionsfor certain components or subassemblies. The mentioned dimensions, orranges of dimensions, are provided in order to comply as best aspossible with certain legal requirements, such as best mode. However,the scope of the inventions described herein are to be determined solelyby the language of the claims, and consequently, none of the mentioneddimensions is to be considered limiting on the inventive embodiments,except in so far as anyone claim makes a specified dimension, or rangeof thereof, a feature of the claim.

The foregoing description details certain embodiments of the invention.It will be appreciated, however, that no matter how detailed theforegoing appears in text, the invention can be practiced in many ways.As is also stated above, it should be noted that the use of particularterminology when describing certain features or aspects of the inventionshould not be taken to imply that the terminology is being re-definedherein to be restricted to including any specific characteristics of thefeatures or aspects of the invention with which that terminology isassociated.

What we claim is:
 1. A single-piece carrier for a continuously variabletransmission (CVT), the single-piece carrier comprising: a generallycylindrical hollow body having a first end, a second end, and a sideformed with a plurality of openings, the plurality of openings extendingfrom an interior surface of the first end to an interior surface of thesecond end to form a plurality of carrier legs, wherein the plurality ofcarrier legs are configured to provide torsional strength to thecarrier, wherein each opening of the plurality of openings isdimensioned to allow passage of a planet, and wherein the plurality ofopenings is asymmetrically arranged so that an idler assembly of the CVTcan pass through at least one opening of the plurality of openings; afirst plurality of radial grooves formed on the first end interiorsurface, wherein the first plurality of radial grooves are accessiblethrough the plurality of openings, and wherein each radial groove of thefirst plurality of radial grooves is formed for contact with a first endof a planet axle; and a second plurality of radial grooves formed on thesecond end interior surface, wherein the second plurality of radialgrooves are accessible through the plurality of openings, and whereineach radial groove of the second plurality of radial grooves is formedfor contact with a second end of the planet axle.
 2. The single-piececarrier of claim 1, wherein the first and second plurality of radialgrooves comprise a substantially toriconical profile.
 3. Thesingle-piece carrier of claim 1, wherein the first and second pluralityof radial grooves comprise a substantially hemi-cylindrical profile. 4.The single-piece carrier of claim 1, wherein the side of the generallycylindrical hollow body comprises a continuous arcuate side.
 5. Thesingle-piece carrier of claim 1, wherein the at least one openingthrough which the idler assembly can pass is larger than at least oneother opening of the plurality of openings.
 6. The single-piece carrierof claim 1, wherein at least one groove of the first plurality ofgrooves is accessible through each opening of the plurality of openings,and wherein more than one groove of the first plurality of grooves isaccessible through at least one opening of the plurality of openings. 7.A system comprising: a single-piece carrier for a continuously variabletransmission (CVT), the single-piece carrier comprising a generallycylindrical hollow body having a first end, a second end, and a side, aplurality of openings formed in the side of the cylindrical hollow bodyand extending from an interior surface of the first end to an interiorsurface of the second end to form a plurality of carrier legs, whereinthe carrier legs are configured to provide torsional strength to thecarrier, wherein each opening of the plurality of openings isdimensioned to allow a planet to pass through the opening, and whereinthe plurality of openings is asymmetrically arranged so that an idlerassembly of the CVT can pass through at least one opening of theplurality of openings, a first plurality of radial grooves formed on thefirst end interior surface, wherein the first plurality of radialgrooves are accessible through the plurality of openings, and whereineach radial groove of the first plurality of radial grooves is formedfor contact with a first end of a planet axle, and a second plurality ofradial grooves formed on the second end interior surface, wherein thesecond plurality of radial grooves are accessible through the pluralityof openings, and wherein each radial groove of the second plurality ofradial grooves is formed for contact with a second end of the planetaxle.
 8. The system of claim 7, wherein the first and second pluralityof radial grooves comprise a substantially toriconical profile.
 9. Thesystem of claim 7, wherein the first and second plurality of radialgrooves comprise a substantially hemi-cylindrical profile.
 10. Thesystem of claim 7, further comprising a first support axle coupled tothe first end of the carrier, the first support axle extending axiallyfrom a first exterior surface of the carrier.
 11. The system of claim 7,further comprising a second support axle coupled to the second end ofthe carrier, the second support axle extending axially from a secondexterior surface of the carrier.
 12. The system of claim 7, furthercomprising a power input assembly.
 13. A method of forming asingle-piece carrier, comprising: forming a generally cylindrical hollowbody having a first end, a second end, and a continuous arcuate side;forming a plurality of openings in the side of the cylindrical hollowbody, the plurality of openings extending from an interior surface ofthe first end to an interior surface of the second end to form aplurality of carrier legs, wherein the carrier legs are configured toprovide torsional strength to the carrier, wherein each opening of theplurality of openings is dimensioned to allow a planet to pass throughthe opening, and wherein the plurality of openings is asymmetricallyarranged so that an idler assembly of the CVT can pass through at leastone opening of the plurality of openings; forming a first plurality ofgrooves on the first end interior surface, wherein the first pluralityof grooves are accessible through the plurality of openings, and whereineach radial groove of the first plurality of radial grooves is formedfor contact with a first end of a planet axle; and forming a secondplurality of grooves on the second end interior surface, wherein thesecond plurality of grooves are accessible through the plurality ofopenings, and wherein each radial groove of the second plurality ofradial grooves is formed for contact with a second end of the planetaxle.
 14. The method of claim 13, wherein the first plurality of groovesand the second plurality of grooves are formed for coupling to an axlefor a power adjuster, and wherein each opening of the plurality ofopenings is formed to allow passage of the power adjuster.